J.T.
Hi A. -
Well, before you dial 411 for SuperNanny, know that this is very common. Annoying as hell, but common. I have a six-year-old daughter (and a 15-year-old son) and we're going through this, too.
What I did with my son, and am doing with my daughter is this:
1) When she whines or complains, I calmly tell her I cannot hear her and explain to her that she must use a tone of voice that is appropriate. If necessary, I model it -- "Mom, could you please help me make a snack?" instead of "Maaaaaaaaam, I'm hungry! Get me something to eat!!!"
2) If she bursts into the room whining or with a demand, I tell her she has to leave the room, come back in, and try again.
3) When she 'gets smart' with me, I explain to her that I do not like that tone and will not talk to her when she uses that tone with me. IGNORE HER. Often this smart talk is purposely provocative to get our attention -- so, don't let it 'work'!
4) If she gets really sassy, tell her, calmly, that she has to go to her room until she speak pleasantly with you. Don't get mad, just temporarily banish her. ;)
5) Remember that kids at this age are normal in their narcissism. The world really is all about them! So, do cut her some slack. The verbal world is still quite new to her, and she's trying out 'her legs'.
6) Finally, make sure that YOU are not speaking to HER in demanding or whining ways. Sadly, we often model the wrong behavior -- I know I do it, too!
Good luck!
J.